Poster: Regulation of gene expression
Abs #
784: Differential expression of chaperone genes in preconditioning for photosynthetic acclimation in drought-stressed Loblolly pine
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Presenter: |
Vasquez-Robinet, Cecilia , cevasque@vt.edu | Authors | Vasquez-Robinet, Cecilia (A) Watkinson, Jonathan I (A) Heath, Lenwood (B) Ramakrishnan, Naren (B) Singhal, Vibha (B) Moura, Catarina (C) Sioson, Allan (B) Shuckla, Maulik (B) Grene, Ruth (A) | | Affiliations: |
(A): Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA,24061
(B): Department of Computer Science, Virginia Tech, Blacksburg, VA 24061
(C): Departmenf of Biology, Duke University, Durham, NC, 27708
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Photosynthetic acclimation in loblolly pine treated with successive cycles of mild drought stress is correlated with specific expression patterns of genes encoding chaperones and enzymes of flavonoid metabolism (Watkinson et al, Plant Phys 133,1702-1716). We report here on a similar experiment, involving roots and needles with a focus on these genes. A progressive treatment, consisting of one cycle of mild stress (-1Mpa) followed by two cycles of severe stress (-1.7Mpa), was included to determine if conditioning would occur. Water was withheld from 1 yr cuttings and drought was monitored by water potential measurements. Net photosynthesis was measured at each stress level. RNA was isolated from roots and needles at the points of maximum stress and 24h after rehydration. RNA was used for hybridization against a microarray consisting of 1800 cDNA stress-related clones. Microarray analysis was carried out as before. Severe treatment did not produce photosynthetic acclimation; however, we observed photosynthetic acclimation in the 2nd and 3rd cycle of the progressive treatment, suggesting that a cycle of mild stress conditioned the trees to adapt to a more severe stress. Microarray results indicated differential expression in genes encoding members of the HSP70 and HSP90 families, specifically between the points of maximum stress and recovery in needles and roots. A homolog to Arabidopsis HSC70.1 showed up-regulation at maximum stress during the 2nd cycle of progressive treatment in needles but also up-regulation at recovery in roots. These results suggest distinct, and tissue-specific roles for these paralogous genes. Real time PCR using SYBR green was used to confirm our microarray results.
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